Potassium Metabisulfite (K₂S₂O₅) - Campden Brewing
Potassium Metabisulfite (K₂S₂O₅), widely known in homebrewing and winemaking circles as Campden, is a food-grade sulfite compound used for sanitisation, antioxidant protection, and chloramine neutralisation across the full range of fermentation-based production. A versatile and indispensable addition to any homebrewer’s or winemaker’s chemical toolkit, Campden works quietly in the background to protect your beer, wine, cider, and mead from oxidation, wild yeast, and bacterial spoilage at every stage of the process.
What makes potassium metabisulfite so widely used across both brewing and winemaking is its broad-spectrum protective action. In winemaking and cider production, Campden inhibits wild yeast and spoilage bacteria in freshly crushed must, providing a clean fermentation environment before pitching a cultured yeast strain. In brewing, its most critical application is chloramine neutralisation — a single Campden tablet or a small measured dose added to tap water immediately and completely eliminates chloramine, the municipal water treatment compound that reacts with brewing compounds to produce chlorophenols: the medicinal, plasticky off-flavour that can ruin an otherwise perfectly brewed batch. Unlike chlorine, chloramine cannot be removed by boiling or carbon filtration alone — Campden is the fast, reliable, and definitive solution.
As an antioxidant, K₂S₂O₅ also protects finished wine, cider, and mead during storage and between rackings — binding free oxygen and preventing premature oxidation that would otherwise flatten aroma and degrade colour over time.
Powder form
Supplied as a fine powder. Dissolves quickly and completely in cold or warm water, must, or wort. Can also be used in tablet form for pre-measured convenience.
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Key Features
• Food-grade potassium metabisulfite (K₂S₂O₅) — Campden
• Eliminates chloramine from tap water instantly — prevents chlorophenol off-flavours
• Inhibits wild yeast and spoilage bacteria in must and juice
• Antioxidant protection during storage, racking, and packaging
• Effective at very low dose rates — highly economical in use
• Suitable for beer, wine, cider, mead, and fruit-based fermentations
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Usage
Beer: Chloramine neutralisation in tap water before brewing — critical for municipal water supplies
Wine & Cider: Must sanitisation before pitching, antioxidant protection between rackings and during storage
Mead: Must treatment and antioxidant protection
Equipment: Low-concentration sanitising solution for equipment and surfaces
Dose: Approximately 0.44g per 20 litres neutralises chloramine in tap water. For must sanitisation, follow style-specific sulfite addition guidelines based on must pH and temperature.
Note: Not suitable for use immediately before pitching yeast at high doses — allow sufficient time for SO₂ to dissipate before adding your yeast culture.
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Quick facts
Product: Potassium Metabisulfite
Common name: Campden
Chemical formula: K₂S₂O₅
Form: Fine powder
Use: Chloramine neutralisation, must sanitisation, antioxidant protection, equipment sanitising